In recent years, as smart phones have been widely supplied, there have been issues as follows. Firstly, because of lack of existing IPv4 addresses, it is urgent to use IPv6 addresses. Secondly, current networks have been designed for fixed nods but smart phones have mobility capability, and, thus, support for mobility is needed.
Thirdly, it is typical for smart phone to support a WLAN and a cellular network at the same time, and, thus, a media independent handover needs to be supported. Fourthly, in order to transmit real-time traffic data such as audio/video through a WLAN as well as a cellular network, an end-to-end delay needs to be considered. Fifthly, considering a situation where usable power is limited, low-power communication needs to be considered.
Further, there are major problems of the current Internet: a semantic overload problem of IP address; and routing scalability. Firstly, the semantic overload problem of IP address is that a current IP address identifies “where” and “who” at the same time. Secondly, the routing scalability is that the routing tables increase due to multi-homing, traffic engineering, and non-aggregatable address allocation.
Furthermore, for ubiquitous environment, a network which is independent and can be self-organized, such as MANET, needs to be considered. As for the MANET, not only communication between internal nodes but information interchange with an external network is important, and, thus, connecting the MANET with external networks needs to be considered.